A dual-flywheel ungrounded haptic feedback system provides single-axis moment pulses for clear direction signals

Flywheel rotation provides a means for ungrounded kinesthetic (force) feedback, but devices that use a single flywheel to generate moment pulses inherently generate undesirable torque in directions orthogonal to the desired torque. We present a novel dual-flywheel gyro-moment haptic device capable of delivering short moment pulses about isolated axes in three-dimensional space. Rotating a single spinning flywheel about an axis creates a reaction moment about an orthogonal axis. Summing the moments created by two flywheels spinning in opposite directions eliminates moment components due to gyroscopic effects, leaving a moment about a constant axis. A dynamic model and torque output measurements of the dual-flywheel system demonstrate that the dual-flywheel approach generates moments about any 3D axis with no orthogonal moment components. We hypothesize that this system presents easily discernible haptic feedback that users can interpret as a direction signal. A prototype device and user study demonstrate experimentally that moment pulses generated by the dual-flywheel system resulted in easily distinguishable direction signals.